Someone just DM’d me a question on Instagram:
“Hi Dr. C, what are the symptoms of too little iodine?”
I’ve talked a lot about the dangers of too much iodine for those prone to thyroid disease.
The data is clear. Iodine is not ‘bad’, our bodies need it.
Yet the single most helpful thing for thyroid health is to be deliberate about how much iodine you get. It is easier to get too much than too little iodine.
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Staying on the low end of the healthy range of iodine intake has been proven to prevent and even reverse nearly all forms of thyroid disease.
Even those who work hard to reduce iodine have little to fear.
Why? Because nearly all foods have some iodine and the thyroid can work just fine on even tiny amounts.
Having said that, it is not impossible to become iodine deficient.
But how likely is an iodine deficiency, and who should worry about it?
This article will give complete answers to these questions. Here is a quick summary if you’re in a rush.
Quick Summary
It is an unusual nutrient in that the tiniest bit too much or too little iodine can cause problems for some people.
The good news: Widespread deficiencies around the globe have been eradicated since 2014.
The bad news: Yet some populations have individuals at risk from too much or too little.
This article will help you understand if you or a patient could be at risk for an iodine deficiency, how to be sure, and what to do about it.
The bulk of this discussion will be about adults who are not pregnant or lactating. I will mention the distinct needs of children and the pregnant, but I’ll specify as such when doing so.
Another important point is that many conditions that appear to be iodine deficiency are in fact caused by iodine excess. One of the consequences of too much iodine is that the thyroid closes the doors so it won’t absorb too much. If the dose is too high and the doors stay closed too long, issues like those of a deficiency can emerge. This is the main reason that too much causes the same problems as too little iodine.
Brian was a 19 year old lanky young man whose father brought him in to see me. Brian had a visibly enlarged thyroid and was told by another doctor that he needed thyroid medication.
Over the last 6 months, Brian had been on a pretty restrictive diet. Like really restrictive. Brian’s dad wondered if his diet could be a factor and if modifying it could be a simpler solution than medications.
Here is some more about his diet. Brian attended a lecture by a famous motivational speaker. At that time, this speaker told the audience that the more raw veggies they ate, the better.
I don’t like the words ‘more’ or ‘less’ when it comes to dietary change. If one continually adds more raw veggies to their diet, at some point they will eat nothing else.
Being a driven young man, Brian took things to extremes. He had been on a healthy omnivorous diet. But the day after the seminar, he changed to only eating raw veggies – mostly broccoli.
Each day he blended many pounds of broccoli, with some carrots, celery, and spinach. That was all he ate. No salt, no other foods at all. He used to have an athletic build, now he was skinny and pale.
Yes, broccoli is a cruciferous vegetable. You may have heard that cruciferous vegetables can cause goiters. They can. There is another published case report of a woman who ate 4-6 pounds of raw bok choy each day and developed a goiter.
Yet these same foods pose numerous benefits and zero risks when used in the context of a healthy diet with lots of variety.
Back to Brian. His dad showed me his blood tests and ultrasound report the last doctor had run. His thyroid function was low-normal, he did not have positive thyroid antibodies. The ultrasound which showed a goiter about 4 times the size of a normal thyroid with no other abnormalities.
I ordered a urinary iodine to creatinine ratio test – Brian’s iodine levels were undetectable.
My sole recommendation was for Brian to return to a healthy diet with a wide range of foods. I did not put him on iodine supplements or suggest high-iodine foods. I agreed with his father that thyroid medication would not be helpful.
One could safely assume that his lack of iodine was compounded by too little iodine in conjunction with too little selenium, iron, and zinc.
We repeated his ultrasound 3 months later and found that his thyroid was just about down to a normal size. He felt much better and had regained about 15 pounds of muscle.
Brian is one of the 7 known cases of iodine deficiency since 1980.
To put it in perspective over that same timeframe 12,000 people were struck by lightning.
It does not happen easily. It requires being low in many other nutrients in addition to iodine. Some of the main ones that are relevant include selenium, iron, zinc, and vitamin A. It also requires being severely deficient for some time, typically 6 months or greater1,2.
There is a difference to consider between being ‘low in iodine’ and being ‘iodine deficient’. To be low in it means that one consumes a small enough amount to be at risk for a deficiency. It does not mean anything goes wrong, it means there is a risk something might happen.
The same thing applies to iodine excess. People can be at risk from iodine excess without having problems emerge. How much iodine someone can tolerate varies from person to person and this is the main reason why some are more prone to thyroid disease than others.
Remember, we DO need iodine. However we don’t need that much iodine.
The estimated average requirement for adults is 95 mcg per day3.
How much specifically? If someone lives to be 100 years old, they will use about 1 tsp of iodine over their entire lifetime.
Pregnant, nursing women, and their babies have the least thyroid problems when mom averages 150-249 mcg per day4,5.
For those on thyroid medication, the medicine itself supplies their iodine6.
Yet among people who are low in iodine, most don’t get symptoms. In fact, most do just fine.
As a case in point, kids are more sensitive to low iodine than adults. A recent study measured the iodine status of children, many of whom were at levels considered deficient. As expected, there were a few children found to have thyroid disease. Yet those who were iodine deficient had no more thyroid disease or other health problems than their peers. In fact, thyroid disease was more common in kids with excess iodine than in those who were even the most severely deficient.
The researchers summarized by saying there is no dispute that some level of iodine deficiency will eventually cause problems, yet:
“Low [iodine] values in our cohort were not associated with impaired thyroid function. Our results suggest that the parameters used to define iodine deficiency for clinical applications need to be revisited7.”
So if you’re wondering about yourself or your patients, here is the process by which one would diagnose an iodine deficiency
If there are no signs of thyroid enlargement, the likelihood of iodine deficiency is low enough to be dismissed. No further steps are needed.
How would someone know they have an enlarged thyroid? They may see it themselves, or it may feel swollen. They might have changes to their voice or a difficulty swallowing. Others may have pointed it out to them or it may have shown up on a physical exam.
There are many unrelated reasons that tissues near or in the thyroid would swell. In fact, it happens to as many as 5% of Americans8.
That means that in any given year, roughly 16.5 million Americans have a goiter. With 7 cases of iodine deficient goiters over 40 years, you could say there is a case every 5.7 years or that each year there are 0.175 cases of iodine deficient goiter.
With 16.5 million cases per year, the odds of a particular person’s goiter being caused by iodine deficiency are about 1/94,000,000. It’s possible, but it sure is not likely!
If the ultrasound suggests Hashimoto’s or any problems other than an unexplained goiter, iodine deficiency is not likely.
If the ultrasound shows no other issues plus the diffuse, even swelling of a goiter, the next step would be to test thyroid levels.
If the patient has positive thyroid antibodies and/or signs of abnormal thyroid function, they are the most likely culprits and should be addressed.
If the patient has no signs of Hashimoto’s and an unexplained goiter, the next step is to ask about their possible iodine intake.
Do they consume animal protein, egg yolks, or seafood?
Do they use salt with iodine, or sea vegetables? Do any of their supplements contain iodine?
If they say yes to more than one of these questions, an iodine deficiency would not be expected, and other causes should be sought.
Goiters can be genetic or related to alcohol or tobacco intake.
If they consume no foods rich in iodine, the next step is to do a urinary iodine to creatinine ratio test.
I’ve talked a lot about the shortcomings of iodine tests for screening. They have too little accuracy to be used to screen people without several signs suggesting iodine deficiency. But in those with no apparent iodine intake and an unexplained goiter, they can be one more piece of data.
At this point, a clinical trial of supplemental iodine is warranted. In the trial, they should receive roughly 100 – 150mcg of iodine per day from dietary sources. I don’t recommend synthetic iodine in supplements because it is poorly regulated. Studies show that iodine in supplements often has 3-4 times the labeled amounts.
How do you get this dose from food?
In the Thyroid Reset Diet, I divided foods into 3 categories: green light, yellow light, and red light.
Green light foods have under 10 mcg of iodine per serving. Yellow light = 10-50 mcg and red light is over 50.
For those who need a little more, I recommend using yellow light foods – 2 or 3 servings. I don’t recommend red light foods because they often have much more than would be helpful.
Examples of one serving include:
In three months, the ultrasound should be repeated. If their goiter has reduced by 30% or more, it was likely caused by an iodine deficiency. If not, other reasons should be considered and supplemental iodine should be discontinued.
Here is a visual algorithm to make this process more intuitive.
Because iodine is in so many foods, even those trying to adhere to a low iodine diet end up averaging about 100 mcg per day9. We think the threshold of deficiency is below 20 mcg per day. Yet even at intakes below that level, many populations show no increase in thyroid problems10.
In closing, an iodine deficiency is possible but not likely. People who avoid high sources of iodine can be rest assured that they will not likely get too little as long as they include many food categories.
Avoiding extra iodine can lower the risk for thyroid cancer
11, breast cancer12, and early mortality13. It has been proven to lower thyroid antibodies14, reverse Hashimoto’s15 and reverse hypothyroidism16.
You can also take the Thyroid Quiz if you’d like to learn more about targeted use of additional nutrients to improve symptoms.
P.S. Whenever you are ready, here is how I can help you now:
1. Schedule a Thyroid Second Opinion with me, Dr. C, Click Here for Details
2. Need A Thyroid Supplement Recommendation? Take My Thyroid Specific Formulations Quiz Now
3. Need a Personalized Supplement? Check out My Thyroid Specific Formulations
4. Download and use my Favorite Recipes Cookbook Here
5. Check out my podcast Medical Myths, Legends, and Fairytales Here
Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.
Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.
Dr. Alan Christianson
Alan Christianson is a Naturopathic Medical Doctor (NMD) who is a board-certified Naturopathic Endocrinologist with a focus on thyroid disorders. He is the author of The Metabolism Reset Diet and the New York Times bestselling book The Adrenal Reset Diet.
He founded Integrative Health, a physician group dedicated to helping people with thyroid disease and weight-loss resistance regain their health.
He has been named a Top Doctor in Phoenix magazine and has appeared on national TV shows and in numerous print media.
Dr. Christianson resides in the woods by a lake in Northern Minnesota with his wife Kirin.
